The present invention relates to hot melt adhesive compositions, wax compositions, and coating compositions, and methods of using the same.
With a view to the environment, a serious need has arisen for biologically degradable products. Various plastic and wax materials, such as hot melt adhesives and protective coatings, are so often used and in such great volume that these products have a significant impact on the environment. A need exists for biodegradable hot melt adhesive and protective coating materials.
Hot melt adhesives are used in a great number of applications and are particularly employed in packaging materials for all sorts of goods. Unfortunately, most conventional hot melt adhesives are non-biodegradable, thus adversely affecting the environment. Those products that claim to be biodegradable are typically based on water sensitive polymers or additives and hence the degradation process is through dissolution rather than biodegradation. A need exists for a biodegradable hydrophobic hot melt adhesive composition that will provide sufficient adhesion for its intended use yet degrade years later and, thus, be environmentally friendly.
Many non-stable products, particularly food products such as cheese, are coated with a synthetic, non-biologically degradable plastic rind to improve product maturation and shelf-life. The plastic of such a rind cannot be recovered or recycled and thus presents a problem for the environment. Furthermore, such a coating must fulfill a large number of functions and a large number of requirements. The coating material must serve to prevent mechanical damage and attack by molds. The coating must offer both mechanical and hygienic protection, and it must be easy to apply, for example, by an immersion coating technique or by coating with a sponge or brush.
Cheese coatings should advantageously affect the luster and rind formation and must adhere well to the wet surface of the cheese. In addition, after drying, the coating must not crack or stick, for example, to cutting boards or other cheeses. The coating should also be semi-impermeable since CO2 and certain flavoring components must be able to diffuse through the coating in order not to adversely affect maturing of the cheese. Water vapor must also be allowed to pass through in a controlled manner so that natural maturing can occur without any question of excessive weight loss. Also, components must not diffuse into the cheese from the coating. Furthermore, the coating must keep well during prolonged storage. Any paraffinic wax layer that is subsequently applied to the latex coating must not peel off after vacuum packaging. In addition, machines used to apply the coating must be easy to clean.
Although biologically degradable and compostable coatings exist, they are generally water-soluble polymers which are consequently water-sensitive. Examples of these are polyvinyl alcohol, polyethylene oxide, and also proteins such as gelatin, casein, and the like. In the past, it has not been possible to use polyhydroxyalkanoate films as coatings in the foodstuffs industry because of the use of organic solvents and because of the need to heat the polyhydroxyalkanoates to the melting point thereof, which could unnecessarily damage the product. A need exists for a polyhydroxyalkanoate protective coating, layer or film that can be used as a protective coating for articles such as food products, in particular, cheese products, and that can be processed at relatively low temperatures and does not require the use of non-consumable organic solvents.
Surface active agents and solvents are also commonly used in a vast variety of industrial products and processes. Because of the large volume of surface active agents and solvents used worldwide in the many industrial product and process applications, a need exists for a new class of surface active agents and a new class of solvents that are biodegradable. Current biodegradable surfactant systems either do not meet required technical specifications or have a significant price disadvantage that make them uncompetitive with synthetic based systems.